1. Field of the Invention
This invention relates generally to removing fluid from a subterranean formation and more particularly to a method for making a well for removing fluid from a desired subterranean formation.
2. Background of the Invention
Subterranean formations often contain desirable fluids that can be used for many applications. Therefore there is need to remove the desirable fluids from the subterranean formation. The subterranean formations often extend horizontally over many thousands of feet and are often very shallow in depth.
One prior art method used to remove desired fluids from a subterranean formation is drilling a horizontal well. The horizontal portion of the well may extend over a significant length of the subterranean formation. When the horizontal portion of the well extends over a significant length of the subterranean formation it intersects multiple natural fractures within the subterranean formation. The natural fractures provide a pathway for fluids to migrate to the well bore.
However, the subterranean formation often contains other fluids beside the desirable fluids that need to be removed before the desirable fluid can be removed. In prior art methods that only use a horizontal well having only a substantially vertical section, curved section and a horizontal section it is difficult to remove the other fluid and thus makes the horizontal well inefficient for removing the desired fluid.
Another prior art method used to remove the desirable fluid from the subterranean formation is drilling a vertical well. However, vertical wells only drain a small amount of desired fluid around the radius of the vertical well because it only intersects a few natural fractures within the subterranean formation without any external stimulation. Thus the vertical well can be inefficient for removing desirable fluid from the subterranean formation.
In prior art methods using a vertical well or a horizontal well it is desirable to use underbalanced drilling. Drilling fluid is often used during the drilling operations. The drilling fluid can be used to remove drilling shavings or cuttings and force them to the surface through circulation of the fluids. If the hydrostatic pressure created by the drilling process exceeds the natural pressure of the subterranean formation the drilling shavings or cuttings may be forced into the formation.
Another method previously used to remove desirable fluids is described in U.S. Pat. No. 6,280,000 issued to Zupanick. This method uses both a horizontal well and a vertical well that intersect each other. This method solves some of the problems of the prior art. However this method requires two wells that can be inefficient and expensive. This method requires a larger well pad site to accommodate both the vertical well and the horizontal well. In addition it is difficult and costly to intersect a vertical well and a horizontal well. This method may require a cavity to be excavated at the bottom of the vertical well that can add additional cost.